Imagine that a buried fuel pipeline, accidentally ruptured by a construction crew, exploded in a fireball in Walnut Creek, and police officers on the scene were unable to communicate with firefighters or other public safety agencies. That’s what happened in 2004 when a contractor installing a water main alongside South Broadway dug in the wrong place and set off an explosion in which five workers were killed.

“Walnut Creek’s radio system was UHF,” said Bill McCammon, former Alameda County fire chief. “The Contra Costa Sheriff, San Ramon PD and County Fire were VHF. They couldn’t talk to one another. There was no communication other than face to face.”

McCammon is the executive director of the East Bay Regional Communications System Authority. If its name is a mouthful, its function is simple: It allows government agencies throughout the 1,500 square miles of Contra Costa and Alameda counties to communicate with one another.

Until the system was activated earlier this month, communication among first responders was an iffy thing.

“Everybody was on different frequencies,” McCammon said. “There were probably 15 different systems. Some agencies were UHF, some VHF, some 800 megahertz.

“If a Richmond police officer was transporting a prisoner to the county jail in Martinez, once he drove out of his coverage area, his radio didn’t even work.”

Digital microwave technology, with strategically placed cells and repeater sites, is what makes the system work, but it was money and cooperation that made it possible.

The project was launched in 2007, after the Department of Homeland Security designated Oakland for funding with its Urban Area Security Initiative Program. Alameda and Contra Costa counties, which shared in the grant as part of the region, formed a joint powers authority, with supervisors, police chiefs, sheriffs, city managers and elected officials from the two counties serving as directors.

It’s rare to find an issue on which any two politicians agree, so the pursuit of unanimity among so many disparate parts has to qualify as the most ambitious aspect of this undertaking.

Six years later, 43 agencies have signed on, with membership including not only municipal police departments, sheriff’s offices and fire districts, but participants such as the Livermore Amador Transit Authority, Caltrans and the East Bay Regional Park District.

None of the members came along for a free ride. When grant money dried up, the two counties supplied financing, secured by subscriber fees charged to users. Every participant in the $72 million project has contributed toward it.

“We felt it was important to gauge the interest of the people participating,” McCammon said. “They had to put some skin in the game. We charged everyone $200 per radio that they were going to operate — we still do when we sign a new agency — and there’s a $40 per month operational fee.”

There are still some subscribers to bring online, but when it’s fully running, the EBRCSA — the government loves acronyms — will serve about 13,000 users in patrol cars, fire stations and elsewhere, supported by an infrastructure that can accommodate even more agencies.

You see, there are a few stragglers that haven’t joined the system. Curiously, one of those is the city that helped make the project possible.